Bug 312514 – [CMake] Add mac-asan preset and fix sanitizer link flags

• Status: RESOLVED
• Resolution: FIXED
• Component: CMake

[zak ridouh]

Add a mac-asan CMake preset for AddressSanitizer builds and fix two
pre-existing bugs that prevented ENABLE_SANITIZERS from working on the
Mac port.

The mac-asan preset uses RelWithDebInfo (optimized + debuggable), enables
ENABLE_SANITIZERS=address, and inherits dev settings (ccache,
compile_commands).

OptionsMac.cmake now mirrors Configurations/Sanitizers.xcconfig by adding
-fsanitize-address-use-after-return=never (disables ASan's fake stack
which breaks JSC garbage collection) and -DRELEASE_WITHOUT_OPTIMIZATIONS
(prevents ALWAYS_INLINE from defeating sanitizer instrumentation). Both
flags are gated to exclude Swift compilation and linking.

Fix unquoted CMAKE_SHARED_LINKER_FLAGS appends in WebKit and
WebKitLegacy PlatformMac.cmake. Without quotes, CMake treats the
expansion as a list, inserting a literal semicolon into the generated
Ninja link command, which the shell interprets as a command separator.
This was latent when CMAKE_SHARED_LINKER_FLAGS was empty but breaks any
build that populates it (e.g. ENABLE_SANITIZERS).

[Radar WebKit Bug Importer]

<rdar://problem/174956971>

[zak ridouh]

Pull request: https://github.com/WebKit/WebKit/pull/62926

[EWS]

Committed 311472@main (2dbae6f74c8d): <https://commits.webkit.org/311472@main>

Reviewed commits have been landed. Closing PR #62926 and removing active labels.